Cmas resistant, high strain tolerant and low thermal conductivity thermal barrier coatings and thermal spray coating method

ABSTRACT

An erosion and CMAS resistant coating arranged on a TBC coated substrate and including at least one porous vertically cracked (PVC) coating layer providing lower thermal conductivity and being disposed over a layer of MCrAlY wherein M represents Ni, Co or their combinations. At least one dense vertically cracked (DVC) erosion and CMAS resistant coating layer is deposited over the at least one PVC coating layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

The instant application claims priority under 35 U.S.C. § 119(e) of U.S.provisional Patent Application No. 62/654,985 filed on Apr. 9, 2018, thedisclosure of which is expressly incorporated by reference herein in itsentirety.

STATEMENT REGARDING SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

BACKGROUND OF THE INVENTION Field of the Invention

The invention is an erosion and Calcium-Magnesium-Aluminum-Silicate(CMAS) resistant multilayer ceramic coating for improving the CMASdegradation issue of thermal barrier coating (TBC) that overlies asuperalloy substrate. The multilayer coating can include an erosion andCMAS resistant dense vertically cracked (DVC) top coat and a low thermalconductivity and strain tolerant porous vertically cracked (PVC)intermediate coating. A coating method is also disclosed.

Description of Related Art

Thermal barrier coatings (TBCs) have been applied onto hot sectioncomponents of gas turbine engines for protection in high temperature.Eight weight percent (8 wt %) Yttria stabilized zirconia (8YSZ) has beenthe historical composition for TBCs due to its high toughness and itslow thermal conductivity up to high temperatures. Non-limiting examplesinclude Metco 222A, 231A, 233A, 233B, 233C and 234A. However, withengine operating temperatures increasing, molten siliceous depositsgenerically known as CMAS attack the 8YSZ TBCs and have been recognizedas a critical factor affecting TBCs durability, and are a fundamentalbarrier to progress in gas turbine technology. Various mitigationstrategies to the problem of CMAS degradation have been attempted. Themost promising strategy seeks to increase the reactivity between thecoating and the CMAS melt. These reactions consume the melt while thecrystalline reaction products form a dense layer and block the paths forfurther melt infiltration. Most of these CMAS reactive TBCs are based onthe rare earth zirconates. However these compositions typically have alower toughness than the 8YSZ coatings. Therefore, a new strategy toincrease CMAS resistant TBCs durability, while keeping the TBCs lowthermal conductivity and high toughness, is essential.

It is also known in the art to employ yttria stabilized zirconia (YSZ)thermal barrier coatings and these have been successfully used in thegas turbine engines for decades. Non-limiting examples include Metco6608 and 6609.

The following documents, which are each herein expressly incorporated byreference in their entireties, disclose various types of DVC coatings;U.S. Pat. No. 8,197,950 to Taylor, issued on Jun. 12, 2012; U.S. Pat.No. 5,073,433 to Taylor, issued on Dec. 17, 1991; US 2014/0178632 toTaylor, published on Jun. 26, 2014; U.S. Pat. No. 5,830,586 to Gray,issued on Nov. 3, 1998; and U.S. Pat. No. 6,703,137 to Subramanian,issued on Mar. 9, 2004.

The following documents, which are each herein expressly incorporated byreference in their entireties, disclose various types of CMAS resistantcoatings; U.S. Pat. No. 6,177,200 to Maloney, issued on Jan. 23, 2001;U.S. Pat. No. 7,875,370 to Schlichting, issued on Jan. 25, 2011; US2012/0034491 to Hongoh, published on Feb. 9, 2012; and U.S. Pat. No.9,023,486 to Nagaraj, issued on May 5, 2015.

The following document, which is herein expressly incorporated byreference in its entirety, discloses a PVC coating; US 2016/0348226 toChen, published on Dec. 1, 2016.

SUMMARY OF THE INVENTION

The invention encompasses an erosion and CMAS resistant multilayerceramic coating for improving the CMAS degradation issue of TBC. Acoating method is also disclosed.

The invention also encompasses a coating system wherein one or more TBClayers are first applied onto a superalloy substrate. Then, one or morelow thermal conductivity strain tolerant layers are applied which areporous vertically cracked (PVC) coating layers. Finally, one or moredense vertically cracked (DVC) erosion and CMAS resistant coating layersare applied or deposited as a top layer.

In embodiments, the porosity of the DVC layer(s) can be 0% to 5% and thecracks can extend either partially through the thickness of thelayer(s), i.e., less than 50% of the thickness, or about 50% of thethickness, and can even extend through an entire thickness of thelayer(s). In embodiments, the cracks can be substantially verticalcracks and can range between 20 and 200 cracks per inch.

In embodiments, the porosity of the PVC layer(s) can be 5% to 25% andthe cracks can extend either partially through the thickness of thelayer(s), i.e., less than 50% of the thickness, or about 50% of thethickness, and can even extend through an entire thickness of thelayer(s). In embodiments, the cracks can be substantially verticalcracks and can range between 20 and 200 cracks per inch.

With this invention, the TBC or coating lifespan can be extended whichextends and improves engine working life.

In embodiments of the present disclosure, a strain tolerant DVC coatingtop layer and the underlying PVC coating system is used to protect theTBC system. The DVC/PVC layers can be composed of tough rare earthelement (Re) stabilized ZrO₂ or HfO₂ mixed with a CMAS resistantchemistry composition. As used herein, CMAS resistant chemistry meansany chemical composition that can react with the CMAS dust and form acrystalline phase to prevent the CMAS further penetration to the coatingor the chemical composition which can improve the CMAS meltingtemperature after reacting with CMAS. The DVC layers provide erosionresistance and the PVC layers decreasing the thermal conductivity.

Main advantages of the invention include the tough Re stabilized ZrO₂ orHfO₂ mixed with CMAS resistant chemistry to improve the erosion and CMASresistance of the TBC system. In addition, a PVC strain toleranttransition layer provides lower thermal conductivity.

Non-limiting embodiments of the DVC top layer(s) and/or the PVClayer(s), with the DVC being erosion and CMAS resistant and with the PVCbeing a thermal barrier and CTE (Coefficient of Thermal Expansion)mitigation layer, include the following (with exemplary rare earthoxides including Yttrium oxide, Lanthanum oxide, Cerium oxide,Praseodymium oxide, Neodymium oxide, Samarium oxide, Europium oxide,Gadolinium oxide, terbium oxide, Dysprosium oxide, holmium oxide, erbiumoxide, ytterbium oxide, Lutetium oxide, Scandium oxide, Thulium oxide):

-   -   RE stabilized ZrO₂ or HfO₂ (RE=rare earth oxides)    -   RE stabilized ZrO₂ or HfO₂ mixture with Rare earth oxides; or    -   RE stabilized ZrO₂ or HfO₂ mixture with Rare earth Silicate; or    -   RE stabilized ZrO₂ or HfO₂ mixture with Rare earth Aluminate; or    -   RE stabilized ZrO₂ or HfO₂ mixture with Rare earth Aluminate        Silicate; or    -   RE stabilized ZrO₂ or HfO₂ mixture with alkaline oxides; or    -   RE stabilized ZrO₂ or HfO₂ mixture with Gadolinium Zirconate; or    -   Any combinations of the above.

The DVC top layer(s) or coating can have a CTE of ˜9×10⁻⁶/degrees C. to13×10⁻⁶/degrees C., as well as a thickness of between 2 mils (0.002inches) and 40 mils (0.040 inches). As used herein, a mil is equal to0.001 inches. This layer or coating can be applied by atmospheric plasmaspraying (APS), plasma spray-physical vapor deposition (PS-PVD) orsuspension plasma spray (SPS).

The PVC intermediate layer(s) or coating can have a CTE of˜9×10⁻⁶/degrees C. to 13×10⁻⁶/degrees C., as well as a thickness ofbetween 1 mil and 40 mils. This layer or coating can be applied byatmospheric plasma spraying (APS), plasma spray-physical vapordeposition (PS-PVD) or suspension plasma spray (SPS).

The bond coating layer(s) or coating can be MCrAlY (M=Co, Ni), with athickness of between 2 mils and 13 mils. This layer or coating can beapplied by atmospheric plasma spraying (APS), high velocity oxy-fuel(HVOF), high velocity air-fuel (HVAF), plasma spray-physical vapordeposition (PS-PVD) or suspension thermal spray.

Non-limiting embodiments of the invention include an erosion and CMASresistant coating arranged on an TBC coated substrate comprising atleast one porous vertically cracked (PVC) coating layer providing lowthermal conductivity and that is disposed over the TBC coated substrateand at least one dense vertically cracked (DVC) erosion and CMASresistant coating layer deposited over the at least one PVC coatinglayer.

In non-limiting embodiments, the at least one DVC layer is a top layer.The coating layer may further comprise at least one bond coating layerdisposed between the TBC and the substrate. The substrate may be asuperalloy substrate.

The at least one dense vertically cracked (DVC) erosion and CMASresistant coating layer may comprise RE stabilized ZrO₂ or HfO₂. The atleast one dense vertically cracked (DVC) erosion and CMAS resistantcoating layer may comprise RE stabilized ZrO₂ or HfO₂ mixed with rareearth silicate. The at least one dense vertically cracked (DVC) erosionand CMAS resistant coating layer may comprise Re stabilized ZrO₂ or HfO₂mixed with rare earth aluminate. The at least one dense verticallycracked (DVC) erosion and CMAS resistant coating layer may comprise Restabilized ZrO₂ or HfO₂ mixed with rare earth aluminate or silicate. Theat least one dense vertically cracked (DVC) erosion and CMAS resistantcoating layer may comprise Re stabilized ZrO₂ or HfO₂ mixed withalkaline oxide. The at least one dense vertically cracked (DVC) erosionand CMAS resistant coating layer may comprise Re stabilized ZrO₂ or HfO₂mixed with gadolinium zirconate. The at least one dense verticallycracked (DVC) erosion and CMAS resistant coating layer may comprise amixture of one or more compositions described above.

The at least one dense vertically cracked (DVC) erosion and CMASresistant coating layer may comprise full thickness vertical cracks. Theat least one porous vertically cracked (PVC) coating layer may comprisefull thickness vertical cracks.

Non-limiting embodiments of the invention include an erosion and CMASresistant coating arranged on an TBC coated substrate comprising atleast one porous vertically cracked (PVC) thermal barrier coating layerproviding lower thermal conductivity and that is disposed over theMCrAlY coated substrate and a top layer of dense vertically cracked(DVC) erosion and CMAS resistant coating material deposited over the atleast one PVC thermal barrier coating layer.

In non-limiting embodiments, the coating may further comprise at leastone bond coating layer disposed between the TBC and the substrate. Thesubstrate may be a superalloy substrate.

The at least one dense vertically cracked (DVC) erosion and CMASresistant coating layer may comprise Re stabilized ZrO₂ or HfO₂ mixedwith rare earth oxide. The at least one dense vertically cracked (DVC)erosion and CMAS resistant coating layer may comprise Re stabilized ZrO₂or HfO₂ mixed with rare earth silicate. The at least one densevertically cracked (DVC) erosion and CMAS resistant coating layer maycomprise Re stabilized ZrO₂ or HfO₂ mixed with rare earth aluminate. Theat least one dense vertically cracked (DVC) erosion and CMAS resistantcoating layer may comprise Re stabilized ZrO₂ or HfO₂ mixed with rareearth aluminate or silicate. The at least one dense vertically cracked(DVC) erosion and CMAS resistant coating layer may comprise Restabilized ZrO₂ or HfO₂ mixed with alkaline oxide. The at least onedense vertically cracked (DVC) erosion and CMAS resistant coating layermay comprise Re stabilized ZrO₂ or HfO₂ mixed with gadolinium zirconate.The at least one dense vertically cracked (DVC) erosion and CMASresistant coating layer may comprise a mixture of one or morecompositions described above.

The at least one dense vertically cracked (DVC) erosion and CMASresistant coating layer may comprise full thickness vertical cracks. Theat least one porous vertically cracked (PVC) coating layer may comprisefull thickness vertical cracks.

Non-limiting embodiments of the invention include an erosion and CMASresistant ceramic coating arranged on a superalloy substrate comprisingan TBC coating layer bonded to the substrate, a porous verticallycracked (PVC) ceramic coating layer providing lower thermal conductivitythat is directly deposited on the TBC coating layer and a densevertically cracked (DVC) erosion and CMAS resistant coating layerdeposited directly on the PVC coating layer. In embodiments, the TBCcoating layer includes a layer of MCrAlY, wherein M represents Ni, Co ortheir combinations.

Non-limiting embodiments of the invention include a method of plasmaspraying an erosion and CMAS resistant coating on an TBC coatedsubstrate, comprising depositing at least one porous vertically cracked(PVC) thermal barrier coating layer providing lower thermal conductivityonto the TBC coated substrate and depositing a dense vertically cracked(DVC) erosion and CMAS resistant coating material over the at least onePVC thermal barrier coating layer.

In embodiments, the TBC coated substrate may comprise at least one bondcoating layer arranged between an TBC layer and the substrate. Theplasma spraying may comprise one of atmospheric plasma spraying (APS),plasma spray-physical vapor deposition (PS-PVD), or suspension plasmaspray (SPS).

Another aspect of the invention provides an erosion and CMAS resistantcoating is arranged on an TBC coated substrate, comprising: at least oneporous vertically cracked (PVC) thermal barrier coating layer providinglower thermal conductivity disposed over the TBC coated substrate; and atop layer of dense vertically cracked (DVC) erosion and CMAS resistantcoating material deposited over the at least one PVC thermal barriercoating layer.

In an embodiment the coating further comprising at least one bondcoating layer disposed between the TBC and the substrate.

In an embodiment of the coating the TBC comprises at least one layer ofMCrAlY wherein M represents Ni, Co or their combinations.

In an embodiment of the coating the at least one dense verticallycracked (DVC) erosion and CMAS resistant coating layer comprises Restabilized ZrO₂ or HfO₂ mixed with rare earth oxide.

In an embodiment of the coating the at least one dense verticallycracked (DVC) erosion and CMAS resistant coating layer comprises Restabilized ZrO₂ or HfO₂ mixed with rare earth silicate.

In an embodiment of the coating the at least one dense verticallycracked (DVC) erosion and CMAS resistant coating layer comprises Restabilized ZrO₂ or HfO₂ mixed with rare earth aluminate.

In an embodiment of the coating the at least one dense verticallycracked (DVC) erosion and CMAS resistant coating layer comprises Restabilized ZrO₂ or HfO₂ mixed with rare earth aluminate or silicate.

In an embodiment of the coating the at least one dense verticallycracked (DVC) erosion and CMAS resistant coating layer comprises Restabilized ZrO₂ or HfO₂ mixed with alkaline oxide.

In an embodiment of the coating the at least one dense verticallycracked (DVC) erosion and CMAS resistant coating layer comprises Restabilized ZrO₂ or HfO₂ mixed with gadolinium zirconate.

In an embodiment of the coating the at least one dense verticallycracked (DVC) erosion and CMAS resistant coating layer comprises amixture of two or more of:

Re stabilized ZrO₂ or HfO₂ mixed with rare earth oxide;

Re stabilized ZrO₂ or HfO₂ mixed with rare earth silicate;

Re stabilized ZrO₂ or HfO₂ mixed with rare earth aluminate;

Re stabilized ZrO₂ or HfO₂ mixed with rare earth aluminate or silicate;

Re stabilized ZrO₂ or HfO₂ mixed with alkaline oxide; and

Re stabilized ZrO₂ or HfO₂ mixed with gadolinium zirconate.

In an embodiment of the coating the top layer of dense verticallycracked (DVC) erosion and CMAS resistant coating layer comprises fullthickness vertical cracks.

In embodiment of the coating the at least one porous vertically cracked(PVC) coating layer comprises full thickness vertical cracks.

In yet another aspect of the invention an erosion and CMAS resistantceramic coating is arranged on a superalloy substrate, comprising: a TBCcoating layer of MCrAlY bonded to the substrate, wherein M representsNi, Co or their combinations; a porous vertically cracked (PVC) ceramiccoating layer providing CTE mitigation directly deposited on the TBCcoating layer; and a dense vertically cracked (DVC) erosion and CMASresistant coating layer deposited directly on the PVC coating layer.

In yet another aspect of the invention a method of plasma spraying anerosion and CMAS resistant coating on an TBC coated substrate isprovided, the method comprising: depositing at least one porousvertically cracked (PVC) thermal barrier coating layer providing lowerthermal conductivity onto the TBC coated substrate; and depositing adense vertically cracked (DVC) erosion and CMAS resistant coatingmaterial over the at least one PVC thermal barrier coating layer.

In an embodiment of the method the TBC coated substrate comprises atleast one bond coating layer arranged between an TBC layer and thesubstrate.

In an embodiment of the method the plasma spraying comprises one of:atmospheric plasma spraying (APS); plasma spray-physical vapordeposition (PS-PVD); or suspension plasma spray (SPS).

Yet another aspect of the invention provides an erosion and CMASresistant coating comprising: at least one porous vertically cracked(PVC) coating layer providing low thermal conductivity disposed over athermal barrier coating (TBC) that includes a layer of NiCrAlY; and atleast one dense vertically cracked (DVC) erosion and CMAS resistantcoating layer deposited over the at least one PVC coating layer.

Yet another aspect of the invention provides a n erosion and CMASresistant coating comprising: at least one porous vertically cracked(PVC) coating layer providing low thermal conductivity disposed over athermal barrier coating (TBC) that includes a layer of CoCrAlY; and atleast one dense vertically cracked (DVC) erosion and CMAS resistantcoating layer deposited over the at least one PVC coating layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide further understandingof the invention and are incorporated in and constitute a part of thisspecification. The accompanying drawings illustrate embodiments of theinvention and together with the description serve to explain theprinciples of the invention. In the figures:

FIG. 1 schematically shows a multi-layer coating in accordance with theinvention; and

FIG. 2 shows a scanning electron microscope (SEM) cross-section of anapplied multi-layer coating in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description illustrates by way of example, not byway of limitation, the principles of the disclosure. This descriptionwill clearly enable one skilled in the art to make and use thedisclosure, and describes several embodiments, adaptations, variations,alternatives and uses of the disclosure, including what is presentlybelieved to be the best mode of carrying out the disclosure. It shouldbe understood that the drawings are diagrammatic and schematicrepresentations of exemplary embodiments of the disclosure and are notlimiting of the present disclosure nor are they necessarily drawn toscale.

The novel features which are characteristic of the disclosure, both asto structure and method of operation thereof, together with further aimsand advantages thereof, will be understood from the followingdescription, considered in connection with the accompanying drawings, inwhich an embodiment of the disclosure is illustrated by way of example.It is to be expressly understood, however, that the drawings are for thepurpose of illustration and description only, and they are not intendedas a definition of the limits of the disclosure.

In the following description, the various embodiments of the presentdisclosure will be described with respect to the enclosed drawings. Asrequired, detailed embodiments of the present disclosure are discussedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the embodiments of the disclosure that may beembodied in various and alternative forms. The figures are notnecessarily to scale, and some features may be exaggerated or minimizedto show details of particular components. Therefore, specific structuraland functional details disclosed herein are not to be interpreted aslimiting, but merely as a representative basis for teaching one skilledin the art to variously employ the present disclosure.

The particulars shown herein are by way of example and for purposes ofillustrative discussion of the embodiments of the present disclosureonly and are presented in the cause of providing what is believed to bethe most useful and readily understood description of the principles andconceptual aspects of the present disclosure. In this regard, no attemptis made to show structural details of the present disclosure in moredetail than is necessary for the fundamental understanding of thepresent disclosure, such that the description, taken with the drawings,making apparent to those skilled in the art how the forms of the presentdisclosure may be embodied in practice.

As used herein, the singular forms “a,” “an,” and “the” include theplural reference unless the context clearly dictates otherwise. Forexample, reference to “a powder material” would also mean that mixturesof one or more powder materials can be present unless specificallyexcluded. As used herein, the indefinite article “a” indicates one aswell as more than one and does not necessarily limit its referent nounto the singular.

Except where otherwise indicated, all numbers expressing quantities usedin the specification and claims are to be understood as being modifiedin all examples by the term “about.” Accordingly, unless indicated tothe contrary, the numerical parameters set forth in the specificationand claims are approximations that may vary depending upon the desiredproperties sought to be obtained by embodiments of the presentdisclosure. At the very least, and not to be considered as an attempt tolimit the application of the doctrine of equivalents to the scope of theclaims, each numerical parameter should be construed in light of thenumber of significant digits and ordinary rounding conventions.

Additionally, the recitation of numerical ranges within thisspecification is considered to be a disclosure of all numerical valuesand ranges within that range (unless otherwise explicitly indicated).For example, if a range is from about 1 to about 50, it is deemed toinclude, for example, 1, 7, 34, 46.1, 23.7, or any other value or rangewithin the range.

As used herein, the terms “about” and “approximately” indicate that theamount or value in question may be the specific value designated or someother value in its neighborhood. Generally, the terms “about” and“approximately” denoting a certain value is intended to denote a rangewithin ±5% of the value. As one example, the phrase “about 100” denotesa range of 100±5, i.e. the range from 95 to 105. Generally, when theterms “about” and “approximately” are used, it can be expected thatsimilar results or effects according to the disclosure can be obtainedwithin a range of ±5% of the indicated value.

As used herein, the term “and/or” indicates that either all or only oneof the elements of said group may be present. For example, “A and/or B”shall mean “only A, or only B, or both A and B”. In the case of “onlyA”, the term also covers the possibility that B is absent, i.e. “only A,but not B”.

The term “at least partially” is intended to denote that the followingproperty is fulfilled to a certain extent or completely.

The terms “substantially” and “essentially” are used to denote that thefollowing feature, property or parameter is either completely (entirely)realized or satisfied or to a major degree that does not adverselyaffect the intended result.

The term “comprising” as used herein is intended to be non-exclusive andopen-ended. Thus, for example a composition comprising a compound A mayinclude other compounds besides A. However, the term “comprising” alsocovers the more restrictive meanings of “consisting essentially of” and“consisting of”, so that for example “a composition comprising acompound A” may also (essentially) consist of the compound A.

The various embodiments disclosed herein can be used separately and invarious combinations unless specifically stated to the contrary.

The invention is described with reference to FIG. 1 which schematicallyshows a multi-layer coating. As is evident in FIG. 1, the multi-layercoating utilizes a top coating layer that is a strain tolerant DVCcoating top layer. This layer is disposed over an underlying PVC coatingsystem which is used to decrease the thermal conductivity of the layers.The DVC/PVC layers can be composed of tough rare earth element (Re)stabilized ZrO₂ or HfO₂ mixed with a CMAS resistant chemistrycomposition. The one or more DVC layers provide erosion resistant andthe one or more PVC layers provide the CTE mitigation between the one ormore high CTE top layer and the one or more low CTE bottom layers ofTBC. The DVC and PVC layer(s) are arranged over a bond coating B andsubstrate S.

The DVC layer(s) can be composed of tough Re stabilized ZrO₂ or HfO₂mixed with CMAS resistant chemistry to improve the erosion and CMASresistance of the TBC/CMC system. In addition, the PVC strain toleranttransition layer(s) provides CTE mitigation between the high CTE toplayer(s) (DVC layer) and the low CTE bottom layer(s) TBC. Next, PVCmicrostructure further reduces thermal conductivity of the TBC system.

Non-limiting embodiments of the DVC top layer(s) and/or the PVClayer(s), with the DVC being erosion and CMAS resistant and with the PVCbeing a thermal barrier and CTE mitigation layer, include the following(with exemplary rare earth oxides including Yttrium oxide, Lanthanumoxide, Cerium oxide, Praseodymium oxide, Neodymium oxide, Samariumoxide, Europium oxide, Gadolinium oxide, terbium oxide, Dysprosiumoxide, holmium oxide, erbium oxide, ytterbium oxide, Lutetium oxide,Scandium oxide, Thulium oxide):

-   -   Re stabilized ZrO₂ or HfO₂    -   Re stabilized ZrO₂ or HfO₂ mixture with Rare earth oxides; or    -   Re stabilized ZrO₂ or HfO₂ mixture with Rare earth Silicate; or    -   Re stabilized ZrO₂ or HfO₂ mixture with Rare earth Aluminate; or    -   Re stabilized ZrO₂ or HfO₂ mixture with Rare earth Aluminate        Silicate; or    -   Re stabilized ZrO₂ or HfO₂ mixture with alkaline oxides; or    -   Re stabilized ZrO₂ or HfO₂ mixture with Gadolinium Zirconate; or    -   Any combinations of the above.

The DVC top layer(s) or coating can have a CTE of ˜9×10⁻⁶/degrees C. to13×10⁻⁶/degrees C., as well as a thickness of between 2 mils and 40mils. This layer or coating can be applied by atmospheric plasmaspraying (APS), plasma spray-physical vapor deposition (PS-PVD) orsuspension plasma spray (SPS).

The PVC intermediate layer(s) or coating can have a CTE of˜9×10⁻⁶/degrees C. to 13×10⁻⁶/degrees C., as well as a thickness ofbetween 1 mil and 40 mils. This layer or coating can be applied byatmospheric plasma spraying (APS), plasma spray-physical vapordeposition (PS-PVD) or suspension plasma spray (SPS).

The bond coating layer(s) or coating B can be MCrAlY (M=Ni, CO) as wellas have a thickness of between 2 mils and 13 mils. This layer or coatingcan be applied by atmospheric plasma spraying (APS), high velocityoxy-fuel (HVOF), high velocity air-fuel (HVAF), plasma spray-physicalvapor deposition (PS-PVD) or suspension thermal spray.

In embodiments, the porosity of the DVC layer(s) can be 0% to 5% and thecracks can extend either partially through the thickness of thelayer(s), i.e., less than 50% of the thickness, or about 50% of thethickness, and can even extend through an entire thickness of thelayer(s). In embodiments, the cracks can be substantially verticalcracks and can range between 20 and 200 cracks per inch or linear inch.In non-limiting embodiments, the DVC layer(s) can also be of a typeknown in the art and described in one or more of the herein incorporateddocuments.

In embodiments, the porosity of the PVC layer(s) can be 5% to 25% andthe cracks can extend either partially through the thickness of thelayer(s), i.e., less than 50% of the thickness, or about 50% of thethickness, and can even extend through an entire thickness of thelayer(s). In embodiments, the cracks can be substantially verticalcracks and can range between 20 and 200 cracks per inch or linear inch.In non-limiting embodiments, the PVC layer(s) can also be of a typeknown in the art and described in one or more of the herein incorporateddocuments.

Non-Limiting Examples

The follow tables include a description of the coating system shown inFIGS. 1 and 2 as well as the parameters used to form the same with aSinplex Plasma Torch.

Chemistry Thickness Plasma Layer composition range torch Process Super-Ni based 3 mm n/a n/a alloy alloy S (sub- strate) bond NiCrAlY ~200 umSinplexPro ™ Ar/H2 coat B plasma gas (bond coat) PVC 7YSZ ~400 umSinplexPro ™ Ar/H2 plasma gas DVC Gd2Zr2O7 ~200 um SinplexPro ™ Ar/H2plasma gas Bond coat PVC DVC layer layer layer Material Amdry 386-4 SeeExamples below Composition NiCrAlYHfSi 8YSZ Gd2Zr2O7 Gun current Amps450 540 500 Voltage Volts 80.5 106 91 Gun power kW 37 57 46 Argon flowNlpm 50 90 70 Hydrogen flow Nlpm 2 7.5 5 Powder feed g/min × 1 50 90 40rate

The follow tables include a description of another coating systemaccording to the invention as well as the parameters used to form thesame with a Sinplex Plasma Torch.

Chemistry Thickness Plasma Layer composition range torch ProcessSuperalloy Ni or Co 3 mm n/a n/a S based alloy (substrate) bond coatCoNiCrAlY ~200 um SinplexPro ™ Ar/H2 B plasma gas (bond coat) PVC 7YSZ~400 um SinplexPro ™ Ar/H2 plasma gas DVC Gd2Zr2O7 ~200 um SinplexPro ™Ar/H2 plasma gas

Bond coat PVC DVC layer layer layer Material Amdry 955C See Examplesbelow Composition CoNiCrAIYi 8YSZ Gd2Zr2O7 Gun current Amps 500 540 500Voltage Volts 91 106 91 Gun power kW 45.4 57 46 Argon flow Nlpm 50 90 70Hydrogen flow Nlpm 4 7.5 5 Powder feed g/min × 1 45 90 40 rate

Further, at least because the invention is disclosed herein in a mannerthat enables one to make and use it, by virtue of the disclosure ofparticular exemplary embodiments, such as for simplicity or efficiency,for example, the invention can be practiced in the absence of anyadditional element or additional structure that is not specificallydisclosed herein.

It is noted that the foregoing examples have been provided merely forthe purpose of explanation and are in no way to be construed as limitingof the present invention. While the present invention has been describedwith reference to an exemplary embodiment, it is understood that thewords which have been used herein are words of description andillustration, rather than words of limitation. Changes may be made,within the purview of the appended claims, as presently stated and asamended, without departing from the scope and spirit of the presentinvention in its aspects. Although the present invention has beendescribed herein with reference to particular means, materials andembodiments, the present invention is not intended to be limited to theparticulars disclosed herein; rather, the present invention extends toall functionally equivalent structures, methods and uses, such as arewithin the scope of the appended claims.

1. An erosion and CMAS resistant coating comprising: at least one porousvertically cracked (PVC) coating layer providing low thermalconductivity disposed over a thermal barrier coating (TBC) that includesa layer of MCrAlY, wherein M represents Ni, Co or their combinations;and at least one dense vertically cracked (DVC) erosion and CMASresistant coating layer deposited over the at least one PVC coatinglayer.
 2. The coating of claim 1, wherein the at least one DVC layer isa top layer. 3.-4. (canceled)
 5. The coating of claim 1, wherein the atleast one dense vertically cracked (DVC) erosion and CMAS resistantcoating layer comprises Re stabilized ZrO2 or HfO2 mixed with rare earthoxide.
 6. The coating of claim 1, wherein the at least one densevertically cracked (DVC) erosion and CMAS resistant coating layercomprises Re stabilized ZrO2 or HfO2 mixed with rare earth silicate. 7.The coating of claim 1, wherein the at least one dense verticallycracked (DVC) erosion and CMAS resistant coating layer comprises Restabilized ZrO2 or HfO2 mixed with rare earth aluminate.
 8. The coatingof claim 1, wherein the at least one dense vertically cracked (DVC)erosion and CMAS resistant coating layer comprises Re stabilized ZrO2 orHfO2 mixed with rare earth aluminate or silicate.
 9. The coating ofclaim 1, wherein the at least one dense vertically cracked (DVC) erosionand CMAS resistant coating layer comprises Re stabilized ZrO2 or HfO2mixed with alkaline oxide.
 10. The coating of claim 1, wherein the atleast one dense vertically cracked (DVC) erosion and CMAS resistantcoating layer comprises Re stabilized ZrO2 or HfO2 mixed with gadoliniumzirconate.
 11. The coating of claim 1, wherein the at least one densevertically cracked (DVC) erosion and CMAS resistant coating layercomprises a mixture of a mixture of two or more of: Re stabilized ZrO2or HfO2 mixed with rare earth oxide; Re stabilized ZrO2 or HfO2 mixedwith rare earth silicate; Re stabilized ZrO2 or HfO2 mixed with rareearth aluminate; Re stabilized ZrO2 or HfO2 mixed with rare earthaluminate or silicate; Re stabilized ZrO2 or HfO2 mixed with alkalineoxide; and Re stabilized ZrO2 or HfO2 mixed with gadolinium zirconate.12. The coating of claim 1, wherein the at least one dense verticallycracked (DVC) erosion and CMAS resistant coating layer comprises fullthickness vertical cracks.
 13. The coating of claim 1, wherein the atleast one porous vertically cracked (PVC) coating layer comprises fullthickness vertical cracks.
 14. An erosion and CMAS resistant coatingaccording to claim 1 arranged on a substrate.
 15. The coating of claim14, further comprising at least one bond coating layer disposed betweenthe TBC and the substrate. 16.-25. (canceled)
 26. The coating of claim14, wherein the substrate is a superalloy substrate.
 27. A method ofplasma spraying an erosion and CMAS resistant coating on an TBC coatedsubstrate, comprising: depositing at least one porous vertically cracked(PVC) thermal barrier coating layer providing lower thermal conductivityonto the TBC coated substrate; and depositing a dense vertically cracked(DVC) erosion and CMAS resistant coating material over the at least onePVC thermal barrier coating layer.
 28. The method of claim 27, whereinthe TBC coated substrate comprises at least one bond coating layerarranged between an TBC layer and the substrate.
 29. The method of claim27, wherein the plasma spraying comprises one of: atmospheric plasmaspraying (APS); plasma spray-physical vapor deposition (PS-PVD); orsuspension plasma spray (SPS). 30.-31. (canceled)